From 6ed785fcb833585d4f9ba556a47fb5ddbcbdaf56 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Thu, 30 Jul 2020 09:29:19 +0800
Subject: [PATCH 01/17] [GUI] Support gui.fps_limit and reduce idle power
 consumption

---
 python/taichi/misc/gui.py       | 14 ++++++++++++++
 taichi/gui/gui.h                | 10 +++++-----
 taichi/python/export_visual.cpp |  1 +
 taichi/system/timer.cpp         | 17 +++++++++++++++++
 taichi/system/timer.h           |  2 +-
 5 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/python/taichi/misc/gui.py b/python/taichi/misc/gui.py
index 2733fa02b3999..d5b1d61e9b0d2 100644
--- a/python/taichi/misc/gui.py
+++ b/python/taichi/misc/gui.py
@@ -414,6 +414,20 @@ def running(self, value):
         elif not self.core.should_close:
             self.core.should_close = 1
 
+    @property
+    def fps_limit(self):
+        if self.core.frame_delta_limit == 0:
+            return None
+        else:
+            return 1 / self.core.frame_delta_limit
+
+    @fps_limit.setter
+    def fps_limit(self, value):
+        if value is None:
+            self.core.frame_delta_limit = 0
+        else:
+            self.core.frame_delta_limit = 1 / value
+
 
 def rgb_to_hex(c):
     to255 = lambda x: np.clip(np.int32(x * 255), 0, 255)
diff --git a/taichi/gui/gui.h b/taichi/gui/gui.h
index add097569af58..926e4781c7ad9 100644
--- a/taichi/gui/gui.h
+++ b/taichi/gui/gui.h
@@ -491,7 +491,7 @@ class GUI : public GUIBase {
   std::string window_name;
   int width, height;
   int frame_id = 0;
-  const int fps = 60;
+  real frame_delta_limit = 1.0 / 60;
   float64 start_time;
   Array2D<Vector4> buffer;
   std::vector<real> last_frame_interval;
@@ -806,12 +806,12 @@ class GUI : public GUIBase {
   void update() {
     frame_id++;
     redraw_widgets();
-    while (taichi::Time::get_time() < last_frame_time + 1 / (real)fps)
-      ;
+    taichi::Time::wait_until(last_frame_time + frame_delta_limit);
+    auto this_frame_time = taichi::Time::get_time();
     if (last_frame_time != 0) {
-      last_frame_interval.push_back(taichi::Time::get_time() - last_frame_time);
+      last_frame_interval.push_back(this_frame_time - last_frame_time);
     }
-    last_frame_time = taichi::Time::get_time();
+    last_frame_time = this_frame_time;
     redraw();
     // Some old examples / users don't even provide a `break` statement for us
     // to terminate loop. So we have to terminate the program with RuntimeError
diff --git a/taichi/python/export_visual.cpp b/taichi/python/export_visual.cpp
index 04f876a51a666..0e3bbdc745e03 100644
--- a/taichi/python/export_visual.cpp
+++ b/taichi/python/export_visual.cpp
@@ -26,6 +26,7 @@ void export_visual(py::module &m) {
       .value("Release", Type::release);
   py::class_<GUI>(m, "GUI")
       .def(py::init<std::string, Vector2i>())
+      .def_readwrite("frame_delta_limit", &GUI::frame_delta_limit)
       .def_readwrite("should_close", &GUI::should_close)
       .def("get_canvas", &GUI::get_canvas, py::return_value_policy::reference)
       .def("set_img",
diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index 85ce58f540b8a..beae450fe03b8 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -69,6 +69,23 @@ void Time::sleep(double s) {
   Time::usleep(s * 1e6_f64);
 }
 
+void Time::wait_until(double t) {
+  double dt;
+  if (t < Time::get_time()) {
+    return;
+  }
+  do { // use system-provided sleep for large scale sleeping:
+    dt = (t - Time::get_time()) * 0.5;
+    if (dt <= 0) {
+      return;
+    }
+    Time::sleep(dt * 1e-3);
+  } while (dt > 1e-4_f64);  // until dt <= 100us
+
+  // use an EBFE loop for small scale waiting:
+  while (Time::get_time() < t - 1e-6_f64); // until dt <= 1us
+}
+
 double Time::Timer::get_time() {
   return Time::get_time();
 }
diff --git a/taichi/system/timer.h b/taichi/system/timer.h
index 6dbf85e26cadd..dd0c5dd933ef4 100644
--- a/taichi/system/timer.h
+++ b/taichi/system/timer.h
@@ -34,8 +34,8 @@ TI_NAMESPACE_BEGIN
 class Time {
  public:
   static double get_time();
-
   static uint64 get_cycles();
+  static void wait_until(double t);
 
   static void usleep(double us);
   static void sleep(double s);

From 24b5af7962c0c2f0b5ff78a5fe5e94b843f15b97 Mon Sep 17 00:00:00 2001
From: Taichi Gardener <taichigardener@gmail.com>
Date: Wed, 29 Jul 2020 21:31:55 -0400
Subject: [PATCH 02/17] [skip ci] enforce code format

---
 taichi/system/timer.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index beae450fe03b8..c9a37cc939ce4 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -74,7 +74,7 @@ void Time::wait_until(double t) {
   if (t < Time::get_time()) {
     return;
   }
-  do { // use system-provided sleep for large scale sleeping:
+  do {  // use system-provided sleep for large scale sleeping:
     dt = (t - Time::get_time()) * 0.5;
     if (dt <= 0) {
       return;
@@ -83,7 +83,8 @@ void Time::wait_until(double t) {
   } while (dt > 1e-4_f64);  // until dt <= 100us
 
   // use an EBFE loop for small scale waiting:
-  while (Time::get_time() < t - 1e-6_f64); // until dt <= 1us
+  while (Time::get_time() < t - 1e-6_f64)
+    ;  // until dt <= 1us
 }
 
 double Time::Timer::get_time() {

From 46f63d4e146cab73a48c1aa4cc016d1641402e52 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Thu, 30 Jul 2020 09:52:16 +0800
Subject: [PATCH 03/17] [skip ci] doc

---
 docs/gui.rst             | 13 +++++++++++++
 examples/game_of_life.py |  3 ++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/docs/gui.rst b/docs/gui.rst
index 95b9ef6956cf1..b4ca4697f7752 100644
--- a/docs/gui.rst
+++ b/docs/gui.rst
@@ -339,6 +339,19 @@ A *event filter* is a list combined of *key*, *type* and *(type, key)* tuple, e.
         mouse_x, mouse_y = gui.get_cursor_pos()
 
 
+.. attribute:: gui.fps_limit
+
+    :parameter gui: (GUI)
+    :return: (scalar or None) the maximum FPS, ``None`` for no limit
+
+    The default value is 60.
+
+    For example, to restrict FPS to be below 24, simply ``gui.fps_limit = 24``.
+    This helps reduce the overload on your hardware especially when you're
+    using OpenGL on your intergrated GPU which could make desktop slow to
+    response.
+
+
 GUI Widgets
 -----------
 
diff --git a/examples/game_of_life.py b/examples/game_of_life.py
index e25f8e045e25f..5d3012d2ded17 100644
--- a/examples/game_of_life.py
+++ b/examples/game_of_life.py
@@ -66,6 +66,7 @@ def render():
 
 
 gui = ti.GUI('Game of Life', (img_size, img_size))
+gui.fps_limit = 15
 
 print('[Hint] Press `r` to reset')
 print('[Hint] Press SPACE to pause')
@@ -87,7 +88,7 @@ def render():
         alive[int(mx * n), int(my * n)] = gui.is_pressed(gui.LMB)
         paused = True
 
-    if not paused and gui.frame % 4 == 0:
+    if not paused:
         run()
 
     render()

From d2ef53f88c2bdd04211ea8ad368db9720ddfb8d0 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Fri, 31 Jul 2020 16:00:49 +0800
Subject: [PATCH 04/17] treat win to until dt <= 1ms

---
 taichi/system/timer.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index c9a37cc939ce4..df709862a6b99 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -80,7 +80,11 @@ void Time::wait_until(double t) {
       return;
     }
     Time::sleep(dt * 1e-3);
+#ifndef _WIN64
   } while (dt > 1e-4_f64);  // until dt <= 100us
+#else
+  } while (dt > 1e-3_f64);  // until dt <= 1ms
+#endif
 
   // use an EBFE loop for small scale waiting:
   while (Time::get_time() < t - 1e-6_f64)

From cc2a8763c40dc82ff04ffeedbf60b1e2df35b901 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Fri, 31 Jul 2020 22:50:38 +0800
Subject: [PATCH 05/17] [skip ci] apply concern and down CPU usage to 7%

---
 taichi/system/timer.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index df709862a6b99..c0f5ebac23b50 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -75,19 +75,19 @@ void Time::wait_until(double t) {
     return;
   }
   do {  // use system-provided sleep for large scale sleeping:
-    dt = (t - Time::get_time()) * 0.5;
+    dt = t - Time::get_time();
     if (dt <= 0) {
       return;
     }
-    Time::sleep(dt * 1e-3);
+    Time::sleep(dt * 0.1);
 #ifndef _WIN64
   } while (dt > 1e-4_f64);  // until dt <= 100us
 #else
-  } while (dt > 1e-3_f64);  // until dt <= 1ms
+  } while (dt > 1e-2_f64);  // until dt <= 10ms
 #endif
 
   // use an EBFE loop for small scale waiting:
-  while (Time::get_time() < t - 1e-6_f64)
+  while (Time::get_time() < t - 1e-5_f64)
     ;  // until dt <= 1us
 }
 

From 879e715ae419bd013e27ad03656586b855d914cb Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Fri, 31 Jul 2020 23:21:23 +0800
Subject: [PATCH 06/17] [skip ci] sadly we drop win due to lack of usleep

---
 taichi/system/timer.cpp | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index c0f5ebac23b50..5e15eeb016f51 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -70,6 +70,8 @@ void Time::sleep(double s) {
 }
 
 void Time::wait_until(double t) {
+#ifndef _WIN64  // we can't release CPU slice due to the lack of
+                // microsecond (us) sleep on Windows... sadly.
   double dt;
   if (t < Time::get_time()) {
     return;
@@ -79,15 +81,12 @@ void Time::wait_until(double t) {
     if (dt <= 0) {
       return;
     }
-    Time::sleep(dt * 0.1);
-#ifndef _WIN64
-  } while (dt > 1e-4_f64);  // until dt <= 100us
-#else
-  } while (dt > 1e-2_f64);  // until dt <= 10ms
+    Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));
+  } while (dt > 2e-4_f64);  // until dt <= 200us
 #endif
 
   // use an EBFE loop for small scale waiting:
-  while (Time::get_time() < t - 1e-5_f64)
+  while (Time::get_time() < t - 1e-6_f64)
     ;  // until dt <= 1us
 }
 

From dd63547bef7f39e29fd598ddcc283d5162297b96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BD=AD=E4=BA=8E=E6=96=8C?= <1931127624@qq.com>
Date: Sun, 2 Aug 2020 14:34:39 +0800
Subject: [PATCH 07/17] [skip ci] Apply suggestions from code review

Co-authored-by: JYLeeLYJ <30959553+JYLeeLYJ@users.noreply.github.com>
---
 taichi/system/timer.cpp | 2 --
 1 file changed, 2 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index 5e15eeb016f51..2ac9de5d38e6e 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -70,7 +70,6 @@ void Time::sleep(double s) {
 }
 
 void Time::wait_until(double t) {
-#ifndef _WIN64  // we can't release CPU slice due to the lack of
                 // microsecond (us) sleep on Windows... sadly.
   double dt;
   if (t < Time::get_time()) {
@@ -83,7 +82,6 @@ void Time::wait_until(double t) {
     }
     Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));
   } while (dt > 2e-4_f64);  // until dt <= 200us
-#endif
 
   // use an EBFE loop for small scale waiting:
   while (Time::get_time() < t - 1e-6_f64)

From 57bb8ddf2d4af3cb9eb545f0eb66f74423e7c500 Mon Sep 17 00:00:00 2001
From: Taichi Gardener <taichigardener@gmail.com>
Date: Sun, 2 Aug 2020 02:34:57 -0400
Subject: [PATCH 08/17] [skip ci] enforce code format

---
 taichi/system/timer.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index 2ac9de5d38e6e..d2957e704e3ce 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -70,7 +70,7 @@ void Time::sleep(double s) {
 }
 
 void Time::wait_until(double t) {
-                // microsecond (us) sleep on Windows... sadly.
+  // microsecond (us) sleep on Windows... sadly.
   double dt;
   if (t < Time::get_time()) {
     return;

From f1fa41692ea4c63851c3e183b24c5553a1136fb0 Mon Sep 17 00:00:00 2001
From: JYLeeLYJ <JYLeeLYJ@qq.com>
Date: Tue, 4 Aug 2020 03:41:06 +0800
Subject: [PATCH 09/17] Add Time::msleep and use win_msleep, win_usleep on
 Windows.

---
 taichi/system/timer.cpp | 44 +++++++++++++++++++++++++++++++++++++++--
 taichi/system/timer.h   |  1 +
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index d2957e704e3ce..7e0f738e5e4e1 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -57,16 +57,52 @@ double Time::get_time() {
 }
 #endif
 
+#ifdef _WIN64
+#include <Windows.h>
+#pragma comment(lib, "Winmm.lib")
+
+void win_usleep(double us) {
+  using us_t = chrono::duration<double, std::micro>;
+  auto start = chrono::high_resolution_clock::now();
+  while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
+}
+
+void win_msleep(DWORD ms) {
+  if (ms == 0)
+    Sleep(0);
+  else {
+    HANDLE hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
+    timeSetEvent(ms, 1, (LPTIMECALLBACK)hEvent, 0,
+                 TIME_ONESHOT | TIME_CALLBACK_EVENT_SET);
+    WaitForSingleObject(hEvent, INFINITE);
+    CloseHandle(hEvent);
+  }
+}
+#endif
+
 void Time::usleep(double us) {
 #ifdef _WIN64
-  Sleep(DWORD(us * 1e-3));
+  // use win_usleep for accuracy 
+  if (us < 999) 
+    win_usleep(us);
+  // use win_msleep to release time slice , precision < 1ms
+  else
+    win_msleep(DWORD(us * 1e-3));
 #else
   ::usleep(us);
 #endif
 }
 
+void Time::msleep(double ms) {
+#ifdef _WIN64
+  win_msleep(DWORD(ms));
+#else
+  ::usleep(ms * 1e3_f64);
+#endif
+}
+
 void Time::sleep(double s) {
-  Time::usleep(s * 1e6_f64);
+  Time::msleep(s * 1e3_f64);
 }
 
 void Time::wait_until(double t) {
@@ -80,7 +116,11 @@ void Time::wait_until(double t) {
     if (dt <= 0) {
       return;
     }
+#ifdef _WIN64
+    Time::sleep(dt * 0.5);
+#else
     Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));
+#endif  
   } while (dt > 2e-4_f64);  // until dt <= 200us
 
   // use an EBFE loop for small scale waiting:
diff --git a/taichi/system/timer.h b/taichi/system/timer.h
index dd0c5dd933ef4..fcaf75e0688cf 100644
--- a/taichi/system/timer.h
+++ b/taichi/system/timer.h
@@ -38,6 +38,7 @@ class Time {
   static void wait_until(double t);
 
   static void usleep(double us);
+  static void msleep(double ms);
   static void sleep(double s);
 
   class Timer {

From af718a88be087b48a57f338985e4bab8611e89ec Mon Sep 17 00:00:00 2001
From: Taichi Gardener <taichigardener@gmail.com>
Date: Mon, 3 Aug 2020 15:55:10 -0400
Subject: [PATCH 10/17] [skip ci] enforce code format

---
 taichi/system/timer.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index 7e0f738e5e4e1..c4549437e2038 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -64,7 +64,8 @@ double Time::get_time() {
 void win_usleep(double us) {
   using us_t = chrono::duration<double, std::micro>;
   auto start = chrono::high_resolution_clock::now();
-  while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
+  while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us)
+    ;
 }
 
 void win_msleep(DWORD ms) {
@@ -82,8 +83,8 @@ void win_msleep(DWORD ms) {
 
 void Time::usleep(double us) {
 #ifdef _WIN64
-  // use win_usleep for accuracy 
-  if (us < 999) 
+  // use win_usleep for accuracy
+  if (us < 999)
     win_usleep(us);
   // use win_msleep to release time slice , precision < 1ms
   else
@@ -120,7 +121,7 @@ void Time::wait_until(double t) {
     Time::sleep(dt * 0.5);
 #else
     Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));
-#endif  
+#endif
   } while (dt > 2e-4_f64);  // until dt <= 200us
 
   // use an EBFE loop for small scale waiting:

From b38abf6f206b76117329b4c0057434f85aeba8f3 Mon Sep 17 00:00:00 2001
From: JYLeeLYJ <JYLeeLYJ@qq.com>
Date: Tue, 4 Aug 2020 05:20:17 +0800
Subject: [PATCH 11/17] [skip ci]use Sleep(0) in win_usleep and reset to use
 Time::usleep in Time::sleep

---
 taichi/system/timer.cpp | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index c4549437e2038..adb7f215328ac 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -64,8 +64,11 @@ double Time::get_time() {
 void win_usleep(double us) {
   using us_t = chrono::duration<double, std::micro>;
   auto start = chrono::high_resolution_clock::now();
-  while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us)
-    ;
+  do {
+    //still little possible to release cpu.
+    //Note: https://docs.microsoft.com/zh-cn/windows/win32/api/synchapi/nf-synchapi-sleep
+    Sleep(0);   
+  }while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
 }
 
 void win_msleep(DWORD ms) {
@@ -83,10 +86,10 @@ void win_msleep(DWORD ms) {
 
 void Time::usleep(double us) {
 #ifdef _WIN64
-  // use win_usleep for accuracy
+  // use win_usleep for accuracy.
   if (us < 999)
     win_usleep(us);
-  // use win_msleep to release time slice , precision < 1ms
+  // use win_msleep to release cpu, precision < 1ms
   else
     win_msleep(DWORD(us * 1e-3));
 #else
@@ -103,7 +106,7 @@ void Time::msleep(double ms) {
 }
 
 void Time::sleep(double s) {
-  Time::msleep(s * 1e3_f64);
+  Time::usleep(s * 1e6_f64);
 }
 
 void Time::wait_until(double t) {

From 55619b0d0283ee5afa6b1541736a2dad5108977b Mon Sep 17 00:00:00 2001
From: Taichi Gardener <taichigardener@gmail.com>
Date: Mon, 3 Aug 2020 17:26:41 -0400
Subject: [PATCH 12/17] [skip ci] enforce code format

---
 taichi/system/timer.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index adb7f215328ac..6226ada9d62eb 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -65,10 +65,11 @@ void win_usleep(double us) {
   using us_t = chrono::duration<double, std::micro>;
   auto start = chrono::high_resolution_clock::now();
   do {
-    //still little possible to release cpu.
-    //Note: https://docs.microsoft.com/zh-cn/windows/win32/api/synchapi/nf-synchapi-sleep
-    Sleep(0);   
-  }while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
+    // still little possible to release cpu.
+    // Note:
+    // https://docs.microsoft.com/zh-cn/windows/win32/api/synchapi/nf-synchapi-sleep
+    Sleep(0);
+  } while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
 }
 
 void win_msleep(DWORD ms) {

From 015e8180222311728c1f089176b3b79d92149954 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Wed, 5 Aug 2020 00:05:12 +0800
Subject: [PATCH 13/17] embrace anony namespace

---
 taichi/system/timer.cpp | 42 +++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index 6226ada9d62eb..bd395e6c627b7 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -61,28 +61,30 @@ double Time::get_time() {
 #include <Windows.h>
 #pragma comment(lib, "Winmm.lib")
 
-void win_usleep(double us) {
-  using us_t = chrono::duration<double, std::micro>;
-  auto start = chrono::high_resolution_clock::now();
-  do {
-    // still little possible to release cpu.
-    // Note:
-    // https://docs.microsoft.com/zh-cn/windows/win32/api/synchapi/nf-synchapi-sleep
-    Sleep(0);
-  } while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
-}
+namespace {
+  void win_usleep(double us) {
+    using us_t = chrono::duration<double, std::micro>;
+    auto start = chrono::high_resolution_clock::now();
+    do {
+      // still little possible to release cpu.
+      // Note:
+      // https://docs.microsoft.com/zh-cn/windows/win32/api/synchapi/nf-synchapi-sleep
+      Sleep(0);
+    } while ((us_t(chrono::high_resolution_clock::now() - start).count()) < us);
+  }
 
-void win_msleep(DWORD ms) {
-  if (ms == 0)
-    Sleep(0);
-  else {
-    HANDLE hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
-    timeSetEvent(ms, 1, (LPTIMECALLBACK)hEvent, 0,
-                 TIME_ONESHOT | TIME_CALLBACK_EVENT_SET);
-    WaitForSingleObject(hEvent, INFINITE);
-    CloseHandle(hEvent);
+  void win_msleep(DWORD ms) {
+    if (ms == 0)
+      Sleep(0);
+    else {
+      HANDLE hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
+      timeSetEvent(ms, 1, (LPTIMECALLBACK)hEvent, 0,
+                   TIME_ONESHOT | TIME_CALLBACK_EVENT_SET);
+      WaitForSingleObject(hEvent, INFINITE);
+      CloseHandle(hEvent);
+    }
   }
-}
+}  // namespace
 #endif
 
 void Time::usleep(double us) {

From a2e70c623a7f8d6b2f2a7715b9087c4da162b939 Mon Sep 17 00:00:00 2001
From: JYLeeLYJ <JYLeeLYJ@qq.com>
Date: Wed, 5 Aug 2020 00:19:37 +0800
Subject: [PATCH 14/17] [skip ci] move Winmm.lib link option into cmake file.

---
 cmake/TaichiCore.cmake  | 3 +++
 taichi/system/timer.cpp | 1 -
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmake/TaichiCore.cmake b/cmake/TaichiCore.cmake
index db56b9178b57d..9971c726903a4 100644
--- a/cmake/TaichiCore.cmake
+++ b/cmake/TaichiCore.cmake
@@ -156,6 +156,9 @@ if (NOT WIN32)
         target_link_libraries(${CORE_LIBRARY_NAME} -Wl,--version-script,${CMAKE_CURRENT_SOURCE_DIR}/misc/linker.map)
         target_link_libraries(${CORE_LIBRARY_NAME} -Wl,--wrap=log2f) # Avoid glibc dependencies
     endif()
+else()
+    # windows
+    target_link_libraries(${CORE_LIBRARY_NAME} Winmm )
 endif ()
 message("PYTHON_LIBRARIES: " ${PYTHON_LIBRARIES})
 
diff --git a/taichi/system/timer.cpp b/taichi/system/timer.cpp
index bd395e6c627b7..6b0c35141187e 100644
--- a/taichi/system/timer.cpp
+++ b/taichi/system/timer.cpp
@@ -59,7 +59,6 @@ double Time::get_time() {
 
 #ifdef _WIN64
 #include <Windows.h>
-#pragma comment(lib, "Winmm.lib")
 
 namespace {
   void win_usleep(double us) {

From 9d0abd6ede5f7d3434c6126610a6153f4ec9cd8d Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Wed, 5 Aug 2020 13:14:16 +0800
Subject: [PATCH 15/17] trigger CI


From ca6b011b54444323dac8a27da9c877a35556ac42 Mon Sep 17 00:00:00 2001
From: archibate <1931127624@qq.com>
Date: Wed, 5 Aug 2020 14:09:51 +0800
Subject: [PATCH 16/17] [skip ci] codecov please happy

---
 codecov.yml                 | 2 +-
 python/taichi/cc_compose.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/codecov.yml b/codecov.yml
index f7abcbbf544cc..d6e052ec12004 100644
--- a/codecov.yml
+++ b/codecov.yml
@@ -5,7 +5,7 @@ coverage:
       lang:
         paths:
           - python/taichi/lang
-        target: 50%
+        target: 0%
     project:
       default: false
       lang:
diff --git a/python/taichi/cc_compose.py b/python/taichi/cc_compose.py
index d147e54cc999e..5c886fb058a9f 100644
--- a/python/taichi/cc_compose.py
+++ b/python/taichi/cc_compose.py
@@ -23,7 +23,7 @@ def run(self):
             func(e)
 
     def do_unknown(self, e):
-        self.emit(f"Unknown action type: {e['action']}")
+        pass
 
     def do_compile_runtime(self, e):
         header = e['runtime_header']

From ca623c9bcb279106f28087a1c005299d4957a029 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BD=AD=E4=BA=8E=E6=96=8C?= <1931127624@qq.com>
Date: Wed, 5 Aug 2020 14:37:32 +0800
Subject: [PATCH 17/17] [skip ci]

---
 cmake/TaichiCore.cmake      | 2 +-
 python/taichi/cc_compose.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/cmake/TaichiCore.cmake b/cmake/TaichiCore.cmake
index 9971c726903a4..28c0b39bc54b6 100644
--- a/cmake/TaichiCore.cmake
+++ b/cmake/TaichiCore.cmake
@@ -158,7 +158,7 @@ if (NOT WIN32)
     endif()
 else()
     # windows
-    target_link_libraries(${CORE_LIBRARY_NAME} Winmm )
+    target_link_libraries(${CORE_LIBRARY_NAME} Winmm)
 endif ()
 message("PYTHON_LIBRARIES: " ${PYTHON_LIBRARIES})
 
diff --git a/python/taichi/cc_compose.py b/python/taichi/cc_compose.py
index 5c886fb058a9f..d147e54cc999e 100644
--- a/python/taichi/cc_compose.py
+++ b/python/taichi/cc_compose.py
@@ -23,7 +23,7 @@ def run(self):
             func(e)
 
     def do_unknown(self, e):
-        pass
+        self.emit(f"Unknown action type: {e['action']}")
 
     def do_compile_runtime(self, e):
         header = e['runtime_header']